TheWrightMan

New Orleans, LA

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Joined: 12/01/2003

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F1-F2 is 280 ohms. How does that sound??
What is the easiest way to polish the slipring??
I also think I found a bad rectifier (CR9) connected between one end of R7 and K1 (starter relay). Looking for some information for a replacement.
LSU Tiger and New Orleans Saints Fan
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TheWrightMan

New Orleans, LA

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Change of info....
Cleaned slip rings and now have 23 ohms across F1-F2.
CR9 was not bad after all.
Megged windings with 500 volt DC megger....
T1-T2 = O ohms T1 & T2 to gnd = .3 megohms
T3-T4 = 0 ohms
Jumped out oil pressure switch...no luck.
Only getting 42 volts AC out of T1 or T3 to T3 or T4 (Neutral).
Still won't stay runnning when you let go of the start button....
Brought the voltage regulator to Onan for testing. Tested capacitor before removing it and it tested good. No news from Onan until next week.
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TheWrightMan

New Orleans, LA

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Cummins-Onan shop can't test voltage regulator. Informed me that they swap it out with another one and if it solves the problem then it's bad.
Is there anyone out there who has the capabilities to test this regulator?
Give me a schematic of what's inside and I can do it.
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TheWrightMan

New Orleans, LA

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Latest update.....
Here is the link to a handy document. http://www.rverscorner.com/onan.html
Checked the voltage regulator using the diode check function on a high quality digital meter. Here are the checks I made:
Open the control box cover and unplug the 12-pin regulator connector. With the meter on 'diode check', test between the following terminal pairs, connecting the positive lead to the first pin and the negative to the second. 5-9, 7-9, 10-9, 11-9, 12-9, 5-10, 5-11, 5-12, 5-3. Voltage regulator is bad if any pair indicates 'short' or 'open' except for pair 5-10, which should indicate open.
It passed this test.
Having removed the voltage regulator I did another test. While the generator was running by holding down the start button I flashed the field (F1-F2) through the brushes with two 9 volt batteries connected in series (18 volts).
Ohmic value across F1-F2 was checked prior to doing this, it was 24 ohms.
During the test, the voltage out of Q1-Q2 was 85 volts AC (this I believe is OK)and the voltage out of T1 & T2 -to- T3 & T4 was 65 volts AC (this certainly is not OK).
Removed the generator from the RV. Expect the problem is internal.
Anyone want to speculate on what the problem will be????
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diesel phil

on the road

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Joined: 10/18/2007

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Mr. Wrightman; I read about your Onan problem, and here is our experience for what it's worth. We recently had our '94 6.5 KW Onan repaired. After 2 years of messing with it. What got my attention about your problem was that it would run as long as you had the start button depressed. That is exactly the symptoms of ours. It was found to be a disconnected governor rod. Ours is on the top of the generator which had to be lowered out of the unit, and the cover removed. I don't know if this has anything to do with your problem but good luck fixing your gen-set. Regards, Phil and Sam in Idaho
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TheWrightMan

New Orleans, LA

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Thanks for the feedback Diesel......
But not generating 120 volts AC is my problem.....not sure how a governor rod would cause this.
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campingking

Akron, Ohio USA

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Joined: 09/22/2003

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I'll throw in my 2 cents since I had the exact same problem on a 6.5 Onan in my 89 Pace Arrow.
Did a lot of what you are currently doing, even put a new control board in it...no luck. Finally took it to it in to be repaired and ended up being the voltage regulator. This regulator is NOT part of the control board but it is located behind the control board and is about the size of a quarter and black.
Hope this helps,
CampingKing
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TheWrightMan

New Orleans, LA

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Campingking....thanks. The control board was the first thing replaced. The voltage regulator was checked using the procedure on the web link I attached. The flashing of field with 18 volts should have produced a 120 volt (or close to it) output voltage. So at this time I do not suspect the voltage regulator and expect to find something wrong internally.
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